Walkthrough ( Video )
1. Accept the quest from Task Master Chang in Job Center.
2. Meet Felix to learn his story. You should get some tokens for him:
1) Red Token
Kill 50 Bandits L97 (around Bird Island 343,261) until the Bandit Leader L97 shows up. When he has been killed, you will obtain a Red Token in your inventory.
2) Indigo Token
You will probably obtain it in your inventory when you kill the Bandit L98 around Bird Island (343,261).
3) Black Token
Kill 10 Bandittis around Bird Island (530,349), and you will find the Bandit Couriers. Kill him and get the Black Token.
4) Pitch Token
Kill 10 Bandit Deliverers on Bird Island (525,345), and get the Pitch Token back.
5) Scarlet Token
Kill the Senior Bandits (Bird Island, 570 417) and you have a chance to obtain the token in your inventory.
3. Disguised as a bandit, you are supposed to meet with Guide Zhang within 90 seconds. He can teleport you to the Bandit Chamber.
4. After you talk to Commander Kerry, you should jump from the shining spots in order, within 10 seconds: blue-green-red-yellow-black.

5. Talk to Kerry again, and bring his message to Felix, when he knows the whole story, he will be thankful and tell you to claim a reward from Task Master Chang in the Job Center.